Control speed and quality in bagging
Equipment and control systems supplier TNA believes it has a solution – one of only a handful of options from suppliers fitting effective metal detection into a confined space. In this case, the company targeted the clearest, shortest route possible between multi-head weighing and bagging.
General manager at TNA Europe Tim Moulsdale said: “At higher speeds, the tendency is for one dump of product to be caught up by the next. ‘Charge compaction’ is the phrase, and the biggest issue is waste: ensuring that product doesn’t get caught in the seal area.”
More direct approach
Rather than including additional equipment, TNA has opted for a more direct approach. “The idea is to get the product out of the bucket as quickly as possible and down the tube former,” said Moulsdale. The problem then is that metal detection between weighing and bagging can change the product’s trajectory, slow it down or string it out.
“We have our hyper-detect system, which sits around the tapered chute between the scale and the bagmaker,” he explained. TNA has a patent for the system, developed in partnership with Mettler Toledo Safeline.
A bagging line currently running at 90 or 100 bags per minute (bpm) might see an increase to 130bpm with hyper-detect, Moulsdale claimed. “It’s that sort of variation. But it’s also moving upwards. It’s all about getting product out of the scale quickly and minimising time in the tube-former.”
This technology, which emerged as a concept about 18 months ago, and last year won the Processing and Packaging Machinery Association (PPMA) Partnership of the Year award, can be combined with TNA’s product-in-seal detection for additional quality control.
TNA is not the only equipment supplier to be looking at these problems. UK sales manager for Lock Inspection Systems Tony Bryant pointed to his firm’s Waferthin vertical fall throat metal detector, also designed to fit between weighing and bagging.
As he explained, bag materials which do not include any foil can be sent through a metal detector after the bagging stage.
‘Much smaller’
“But there may be no space for a conveyorised system after the bagger and, in a vertical fall system, the detection aperture tends to be much smaller,” said Bryant.
Regarding charge compaction, Moulsdale at TNA said that other manufacturers’ systems included volumetric discharge mechanisms. But he was critical of the inclusion of this added complexity: “These are additional mechanical devices which require maintenance and cleaning in one of the least accessible parts of the line.”
